Grumpy Ninja: a Children’s Book About Gratitude and Pespective. When things don't go his way, Grumpy Ninja's mood takes a dive and he becomes super grumpy. So when the pencil sharpener refuses to work, it makes Grumpy Ninja lose control of his emotions. Until one day, a friend shows him how a little gratitude and a simple change of mindset can change his perspective, even when things go wrong. Find out what happens in this book about how a little gratitude might change your perspective.